Vacuum tubes have been used for decades in the well-known medical X-ray technology field as X-ray sources for generating ionizing X-radiation. In these applications an electron beam is emitted from a metal filament cathode heated to over 1000° C. in an evacuated glass tube and accelerated toward a metal anode made, for example, of tungsten, as a result of which X-radiation is generated. A vacuum tube of said kind having a rotating anode is known from U.S. Pat. No. 4,326,144, for example. Known vacuum tubes have among other things the disadvantages of heavy weight (both due to their intrinsic weight and due to an additionally necessary water cooling system), large dimensions, a low level of efficiency, and in particular significant heat generation.
New interventional X-ray applications impose increasingly exacting demands in terms of image quality; at the same time it is important to keep exposure of patients and staff to X-radiation to a minimum. According to the prior art conventional X-ray emitters and flat-panel X-ray detectors are currently used for interventional X-ray systems. Limiting factors affecting image quality in this case are, inter alia, scattered radiation and the limited efficiency of the detector.